1. Field of the Invention
This invention relates generally to a weighted insert for use with shoes in order to make the shoe relatively more massive, thereby tending to strengthen the legs, ankles and feet of the wearer. More specifically, the device according to the present invention relates to an improved configuration of a weighted insole.
2. Description of Related Technology
The use of weighted shoes, or weighted shoe accessories, is well known in the prior art for the purpose of strengthening human leg muscles. When an athlete trains or exercises the legs and feet in a normal manner without the use of abnormally massive shoes, the strengthening of the legs and feet reaches a plateau beyond which no further improvement may be achieved. The addition of weights to the shoes, ankles or lower legs forces the development of stronger muscles which could not be achieved through other normal training methods.
An example of a weighted shoe accessory is disclosed in U.S. Pat. No. 3,306,610, issued to Biggs. Biggs discloses a pair of spats which are placed around the shoe and which contain weights or pockets at various locations such that the amount of weight and its location may be varied according to the needs of the user. While the Biggs device achieves its goal of applying additional weight to the wearer's feet, it suffers the drawbacks of being both asethetically unacceptable and relatively inconvenient to install and remove. The Biggs device requires that it be placed on the external surface of the shoe and secured by lacing, the lacing being necessarily relatively elaborate in order to prevent the weights from shifting when in use. The configuration of the Biggs device is such that its removal is required whenever the shoe is being used in a non-weight training context, since its appearance is very conspicuous and is incompatible with any sort of stylish appearance.
An improved weight training device is disclosed in U.S. Pat. No. 4,252,315, issued to Kimura. Kimura addresses the problems created by the Biggs device by placing the weight in an insert which is placed on the insole of a shoe. The Kimura device suffers from the drawbacks of being insufficiently flexible so as to cause discomfort to the wearer's feet, since it is unable to conform to the individual wearer's foot contour. Additionally, a configuration as disclosed by Kimura results in uncontrolled stress fractures and chafing, the chafing creating sharp burrs on adjacent edges of the base metal. This chafing eventually results in tearing of the padded material surrounding the base metal and, in extreme cases, penetration of the wearer's foot. The rigidity and chafing of the Kimura device tends to make its use quite uncomfortable after a short period of time.